OverClocking an i5-760 2.8 to 4.2-4.4ghz!

[MUZIC FR3AK]

Need some help with overclocking my CPU, its the first gen i5 and I want a little bit more power (I won't be getting a new CPU for a while).
Right now my CPU is a 4.2 Ghz with a 1.4 Vcore voltage. It will run Prime95, but after 7-10 minutes it will down-clock to 1.8 Ghz for a few seconds and OC back to 4.2. Can someone with the same CPU point me to the right direction

Vcore: 1.4 V
Multiplier: 21
Bus Speed: 200

[Domestic_Ginger]

How are your temps? Sounds like it may be throttling or prime has just finished a run.

1.4v is apparently max voltage. I would Google for oc guides for the 1156.

[MUZIC FR3AK]

Max temp under 100% load is 60c. I think the CPU is getting old...